International Journal of Advanced Engineering Research and Science (IJAERS)
https://dx.doi.org/10.22161/ijaers.5.8.29
[Vol-5, Issue-8, Aug- 2018]
ISSN: 2349-6495(P) | 2456-1908(O)
Fuzzy Method for in Control Acetaldehyde
Generation in Resin Pet in the Process of
Packaging Pre-Forms of Plastic Injection
Carlos Alberto Monteiro1, Emanuel Negrão Macêdo2, Manoel Henrique Reis
Nascimento3, Carlos Alberto Oliveira de Freitas4, Jorge de Almeida Brito
Junior5
1 Research
Department, Federal University of Pará (UFPA)
Email: monteiro.marca@gmail.co m
2 Research Department, Federal University of Pará (UFPA)
Email: enegrao@ufpa.br
3 Research Department, Institute of Technology and Education Galileo of the Amazon (ITEGAM)
Email: hreys@itegam.com.br
4 Research Department, Institute of Technology and Education Galileo of the Amazon (ITEGAM)
Email: carlos.freitas@itegam.com.br
5 Research Department, Institute of Technology and Education Galileo of the Amazon (ITEGAM)
Email: jorge.brito@itegam.com.br
Abstract—In order to control the drying temperature of
the PET resin in the silo of the plastic injection molding
machine, during the plastic injection process in the
industries producing preforms for the manufacture of
beverage bottles, care is taken in the ideal temperature
regulation for the better performance in controlling the
generation of Acetaldehyde (AA), which alters the taste of
carbonated or non-carbonated drinks, providing a citrus
nuance to the palate and questioning the quality of the
packaged products The objective of this work is to
develop a tool based on Fuzzy logic to support the control
of the drying temperature of PET resin, allowing
specialists to make the ideal temperature control
decisions necessary to control the generation of
Acetaldehyde (AA). For the development of the proposed
Fuzzy inference model, we used the Matlab Fuzzy toolbox
tool, where the input variables, the fuzzyfication rules and
the output variable were implemented based on the data
collected from the preform injection process. From the
inference model, we obtained a more precise management
of the variables that influence the generation of AA,
estimating a reduction of $ 240,044.00 in annual costs in
the production of preforms.
Keywords— Packaging, Fuzzy Logic, Inference Rules,
Computational Intelligence, PET, Acetaldehyde.
I. INTRODUCTION
With the advent of modern life, the search for
convenience and better quality of life, have enabled the
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increase of research and development of new technologies
and raw materials generate new products.
In this context, processes that evolve the manufacture
of plastic products have shown a considerable increase
(PIRA, 2017).
Regarding the technology used glass as a raw material
in the packaging of soft drinks and water. Polyethylene
terephthalate (PET) in its bioriented form is the most
popular plastic materials to replace glass containers of
drinking water, mineral water and carbonated beverages.
The resin properties and has some advantages, such as
cheaper cost, packaging Lightweight, high mechanical
and chemical resistance, versatility of shapes and colors,
high barriers to gases, excellent transparency and
gloss(ÖZLEM, 2008).
PET or poly (ethylene terephthalate) PET is known
worldwide as classified chemically as a semi crystalline
polyester polymer belonging to the family, suitable
thermoplastic for many applications, particularly in the
packaging industry, and particularly in bottles for
carbonated beverages. The packaging for this type drinks
require special properties, mainly carbon dioxide
permeability, PET application come prove their
acceptance by the market as a fully recyclable material, is
aligned to global trends of economy, energy and
environmental protection(GHISOLFI, 2009).
Recent research shows that PET packaging in the
world market should reach levels of 21.2 million tons by
2021. In 2015 the PET bottles totaled 16.7 million tons,
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representing an increase of about 3, 8% compared with
the previous year 2014. In the year 2016 the growth of
packaging was around 17.5 million tons, achieved an
increase of 4.8%. This growth was due to the
development of new products for application in various
areas of the canning industry, juices and other functional
drinks, forecast the drop in PET resin prices will benefit
the consumer market(PIRA, 2017).
The PET bottle is produced in the injection process
originally in the preform of the bottle, and during this
process the polymers soften with temperature, normally
pass through several stages of heating the material,
followed by mechanical forming, there are several
methods that are used in production of plastic parts as
extrusion,
injection
molding,
blow
molding,
etc.(ROSATO, DONALD, & MATTHEWS, 2004).
They are produced through two processes, injection
and blow, depending on the final part application during
the process of injection molding, which consists
essentially in heating and softening of the material grain
in a heated cylinder and its subsequent injection at high
pressure to the mold, where it cools and takes final
shape(GHISOLFI, 2009).
The entire injection process for obtaining molded
parts is divided into five stages: drying (bin), feed,
plasticization, injection and extraction of the
parts(GHISOLFI, 2009).
PET is a hygroscopic material absorbs environmental
water during storage (storage), careful drying is
controlled in the PET resin and is an essential operation
prior to processing to obtain required levels of drying are
required peripherals such as bin (store), drying with
desiccants, typically with molecular sieves where the air
used for drying of the resin is previously dehumidified,
polymers and PET are no exception where the
temperature range at the recommended drying, should be
between 4 to 6 hours otherwise occurs excessive
temperatures can damage the raw material, the
temperature of the dry air used for drying should be
between 160 ° C - 180 ° C (measured at the dryer outlet)
when the dry air temperature must not exceed 190 ° C
(GHISOLFI, 2009).
A problem came up and the formation of acetaldehyde
during polymerization of the PET resin, typically a
polymer produced by a polymerization process in liquid
phase followed by solid phase polymerization to provide
characteristics appropriate for use in the manufacture of
blown containers for various applications. It is a colorless,
volatile substance citrus odor is generated at high
temperatures(ANJOS, 2007).
This problem is compounded during the injection
process of the preform of PET, PET generated when the
polymer is exposed to high temperatures normally used
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during the injection molding process. When the polymer
is heated above the melting temperature, and may
generate the AA altering the flavor of the carbonated
drink packaged and not aerated (BACH, Dauchy,
Chagnon, & Etienne, 2012).
But it is possible to keep the formation of
acetaldehyde in PET bottles at low levels during the
production process, controlling the critical steps of the
injection process. The concern with the specifications
required by the packaging quality control, processing
conditions to have a bottle with low AA content during
processing of PET resin are low-temperature molten
resin, low shear rate, low time residence(ÖZLEM, 2008).
Artificial Intelligence (AI) techniques applied in the
field of plastic injection process aimed at helping in the
decision to select values for the process parameters
deducted a qualitative inspection of injection defects.
Also aiming at optimizing the process conditions to
obtain a specific level of quality.
The development of systems for operations in the
injection molding process suggests optimal conditions of
control parameters based on IA which is a great degree of
relationship in process conditions (CHAVES, Márquez,
Pérez, Sánchez, & Vizan, 2018).
The AI in injection molding machines may have an
important contribution in the production of plastic parts
quality, due to the action of the sensors that monitor
variations in the temperature of the grains subject to
factors that may come to disqualify the results obtained in
injection (LABATI et al., 2016).
This work has as main objective the use of a fuzzy
inference model for control of acetaldehyde formation in
the plastic injection process of the preform for the
production of bottles.
II.
LITERATURE REVISION
2.1 The Injection Mold
The injection molding is the most widely used
method in the manufacture of plastic products, due to the
high efficiency and manufacturability. The molding
process includes three stages: filling, cooling and
extraction. The first stage begins by filling the mold
cavity with the molten polymer in an injection
temperature, the polymer melt is packed into the cavity at
a higher pressure to compensate for the anticipated
shrinkage as the polymer cools (solidifies) in this cooling
phase, when the part is sufficiently rigid to be extracted
from the mold, care is redoubled because this ph ase
directly affect and especially productivity and quality
molding (CHEN, LAM, & LI, 2000).
The injection molding process is a controllable
process in the specified limits. The injection molding can
be manufactured with a single cavity or a larger number
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of similar or dissimilar cavities, the cavities are
interconnected through flow channels or runners, which
direct the flow of molten plastic material into the cavities.
The manufacturing process of molded parts has five
steps: drying, food, lamination, injection and extraction of
the product. The cooling time in the manufacturing
process, it is important that the injection cycle is from the
start of injection until opening the mold for extracting the
work piece, this time is associated with the solidification
temperature (GHISOLFI, 2009).
The cycle of injection of the preform is performed as
follows: mold closing; injection unit of advancement;
Injection; Repression; Retreat (machine gun); Dosage;
Opening the mold and extraction of the piece. Other
processes for the production of PET containers can be
made by three methods (GHISOLFI, 2009):
Injection stretch blow: the preform produced is then
reheated and stretched and molded into final
packaging. This process is called ISBM (Injection
Stretch Blow Molding) - Injection molding, stretching
and blowing process of a stage;
Injection blow: the preform is produced, then reheated
and blown to stay in the shape of the final package.
This process is called IBM (Injection Blow Molding)
injection and blow-molding by.
Injection: a preform is produced and stored and then
forwarded to the area for blowing production of the
package.
The injection molding machines meet different quality
requirements for specific mold parts such as dry cycle,
injection rate and injection pressure(ROSATO et al.,
2004). The types of injection molding machines can be
identified by their three most popular methods of
operation are: hydraulic, electric and hybrid.
It is observed laminating two basic systems, the first is
the molding of a single stage system (Figure 1) and the
second of two stages (Figure 2). There are also molding
units in three stages, etc. This is known as single-stage
reciprocating screw injection molding machine. The
double stage is the piggyback, which may partially be
related more to a continuous extruder(ROSATO et al.,
2004).
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Fig.2: Cannon plasticizer double injection molding
machine.
Source: (ROSATO et al., 2004).
One of the important and significant processes of this
step is the drying of PET polymer. In solid form PET
polymer to be hygroscopic, it absorbs moisture until the
equilibrium value with the local relative humidity and
high relative humidities in environments can reach up to
0.6% (w / w) by weight if exposed without any protection
and weathering for long periods. In practice the polymer
is stored indoors, properly packaged and for short periods
of time, the humidity value is less may be less than 0.1%
(w / w) or less of the weight before entering the polymer
melt because it will hydrolyze, reducing the molecular
weight and thus the physical properties, chemical and
physico-chemical as(BACH et al., 2012).
If the resin is subjected to fusion with these levels of
moisture, undergoes rapid degradation (hydrolysis),
thereby reducing its molecular weight (Figure 3), which is
reflected in the loss of intrinsic viscosity (IV) and
consequent loss of its physical properties. To maintain the
maximum performance of the PET polymers should
reduce its moisture content to below 0.003% (30
ppm)(GHISOLFI, 2009).
The careful and controlled drying of PET resins is an
essential operation before processing.
H2O
O
–O–CH2–CH2–O–C–
O
–C–O
O–CH2–CH2–OH + HO–C–
–C–O
Fig.3: Reaction hydrolytic degradation (hydrolysis) of
PET resins.
Source: (GHISOLFI, 2009).
Fig.1: Cannon simple plasticizing injection molding
machine.
Source:(ROSATO et al., 2004).
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2.2 Acetaldehyde
The (AA) is a colorless volatile liquid substance and
pungent odor, non-toxic, with odor and taste typical of
fruit, low limit of human perception. AA large quantities
are found naturally in many foods such as fruits, butter,
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cheese, vegetables and beverages (EWENDER &
WELLE, 2008).
The AA is miscible in water and various solvents,
which being in diluted concentrations presents citrus fruit
aroma. The most common synonyms are ethanol
acetaldehyde, acetic aldehyde, acetaldehyde, etilaldeído,
and diethyl 1,1 - dietioxiétano, whose molecular structure
(Figure 4)(NIJSSEN, KAMPERMAN, & JETTEN,
1996).
Fig.4: Structural formula of acetaldehyde.
Source:(GHISOLFI, 2009).
2.3 Generation of acetaldehyde in manufacturing the
resin
In the production of PET resin, AA is formed during
the polymerization stage, which takes place in the melt
phase. The amorphous grain obtained at this point may be
between 50 ppm and 100 ppm AA as temperatures and
residence times used in the process. This resin is postcondensed in the solid state up to a molecular weight
suitable for manufacturing bottles. During this step, the
AA diffuses out of the grain along with the glycol being
driven by process N2. Thus, the AA in PET bottle out of
the solid post-condensation step achieves lower residual
AA levels of 3-4 ppm, depending on the desired
specification for the beverage manufacturer and could
reach levels below 1 ppm(GHISOLFI, 2009).
The resin is intended for transformers, which is
mainly subjected to injection blow molding process. In
this process, the resin is remelted in the injection phase,
then taking place again degradation of the resin, thus
generating AA(NIJSSEN et al., 1996).
2.4 Generation of acetaldehyde in the molding
process
In the resin molding process (PET) the melting
temperature is a key control the generation of variable
formation of acetaldehyde (AA) is in the process
consisting essentially of softening the material in a heated
cylinder (ROSATO et al., 2004).
In the production of PET resin for packaging can be
produced with low levels of residual acetaldehyde (AA),
this waste is generated during melting of the polymer in
the injection molding of the preform. Therefore, it is
important to control the injection process in which the
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polymer is subjected to high temperatures for prolonged
periods fusion(EWENDER & WELLE, 2008).
Besides the residence of the fusion temperature, we
have to consider other relevant factors which are
responsible for acetaldehyde levels found in PET
containers as type and formulation of the resin, type of
equipment, thread profile design of the barrel of the
injection machine and processing conditions (ANJOS,
2007).
Initially only the glass kept this property as required to
properly package the carbonated and meet the
manufacturer's requirements for packaging these products
while maintaining the desired transparency. PET bottles
obtained in injection and blowing process, allowed to
gather optical properties, mechanical and permeability
required for preparation of these carbonated beverages or
non-(GHISOLFI, 2009).
The flavors and aromas in beverages groups may be
altered by the presence of (AA) from the environment
may be, the product itself and / or the packaging material
used. From the point of environmental contamination
arising view, can be diverse sources such as combustion
of wood, coffee roasting, acetic acid and vinyl acetate
production from ethylene, among others. The synthesis or
the formation in the food itself comes also in different
ways, mainly by oxidation of the primary alcohol ethanol
or ethyl and fermentation processes for the production of
foods and beverages(GHISOLFI, 2009).
Concern about the presence of acetaldehyde in PET
packaging is due to the taste change that may cause the
packaged product. For example, colas and mineral water
in which its flavor is directly affected by the presence of
AA. The non-carbonated mineral waters are more
sensitive, resulting in a low perception threshold to the
taste in the range of 20 ppm to 40 ppm AA, depending on
the water composition(EWENDER & WELLE, 2008).
Acetaldehyde is a byproduct of PET degradation,
formed when PET polymer is subjected to high
temperatures, typically used in manufacturing and
processing, when the polymer is heated above the melting
temperature and maintained its high residence
time(NIJSSEN et al., 1996).
Two mechanisms are proposed for AA formation by
thermal decomposition of PET. The first is the thermal
decomposition of hydroxyethyl end group (Figure 5), the
second considers that degradation occurs preferably by
random scission of the molecular chain of the PET with
breaking of ester bonds. This degradation chains are
formed with acids and vinyl terminal groups that can react
in various ways, eliminating AA (Figure 5)(GHISOLFI,
2009).
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O
O
COCH2CH2OH
COH + CH3CHO
PET
acetaldeído
Fig.5: Thermal Degradation of hydroxyethyl end groups.
Source:(GHISOLFI, 2009).
The thermal decomposition of PET (Figure 6) is
significant when the polymer is melted (temperature
above 245 ° C). Therefore, AA is formed so as to
manufacture the resin during processing.
O
O
COCH2CH2OC
PET
O
O CH3 O
COCH = CH2+HOC
COCHOC
Grupo éster-vinílico
Grupo diéster de etilideno
O
O
HOCH 2CH2OC
O
O
OO
COCH2CH2OC
C–O–C
+
anidrido
CH3CHO
acetaldeído
+
CH3CHO
acetaldeído
O
HOCH2CH2OC
O
O
COCH2CH2OC
O
+ HOC
Fig.6: Mechanism of thermal degradation of PET.
Source:(GHISOLFI, 2009).
AA Measurements made in various phases of the
injection blow molding process for preforms of bottles,
confirm that the major source of AA generation on PET
resin transformation process occurs during injection of
the preform due to reflow of resin (GHISOLFI, 2009).
AA generated during injection blow the PET is held in
the bottle wall between the polymer molecules, spreading
slowly to the contents thereof.(EWENDER & WELLE,
2008)
AA generation control in the manufacture of bottles,
the AA formed in the bottle depends on(GHISOLFI,
2009):
Resin Formulation - Aiming at the highest quality
grade resins, formulations were developed and
process conditions that result in lower residual AA
content in the grains.
Processing Conditions - The general processing
conditions for a bottle with low AA content during
the processing of PET are: Low temperature molten
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resin, low shear rates and short residence times (very
long injection times corresponding to increased
exposure heat).
AA is generated at significantly elevated
temperatures. Thus, control of the injection process is
critical to control the AA generation in the production of
bottles. On the other hand, the blowing stage has virtually
no effect on the formation of AA, since it works at
warmer temperatures.
Thus, to reduce the generation of AA from the resin
during the injection of the preform, it is advisable to keep
the polymer melt in the lowest temperature possible for
the minimum time, with minimum shear.
The concentration of AA in the preform increases in
proportion to the drying temperature, the barrel and the
mold. But only adjust the barrel temperatures and mold
channels does not guarantee that the temperature of the
molten polyester go stay fit. The viscous melt is also
heated by friction with the barrel, the screw and the
distribution channels. This friction is much depending on
the viscosity of the molten resin as the type and speed of
the thread. Besides the heat generated by friction, shear
mechanically break the polymer molecules, thereby
forming more hydroxyethyl end groups, which, in turn,
make more AA (Figure 5)(GHISOLFI, 2009).
Parameters to be controlled to minimize exposure to
heat are:
a) cylinder temperature (decrease).
b) Temperatures of hot runner nozzles and manifold
(lessen).
c) residence time in the barrel, and hot runner manifold
(keep as short as possible).
d) Residence time of the polymer melt in the process.
A parameter of almost equal importance to the
temperature of the molten polymer to minimize the
formation of AA in the preform is the residence time
thereof. Put simply note that the AA generated is almost
directly proportional to the residence time of the melt in
the process. Thus, it is a good rule to minimize the cycle
time to decrease the generation of AA. Parameters that
depend on the machine used: Dimensions of injection
channels, the thread profile.
Since low AA concentrations already affecting the
organoleptic properties of the mineral waters and colas
manufacturing bottles with low AA is essential for the
rigid packaging industry. Therefore, it is leading the AA
analysis in quality control resins and bottles (EWENDER
& WELLE, 2008).
2.5 Fuzzy theory
The fuzzy set theory was developed in 1965, with the
work of Lotfi Zadeh, professor at the University of
California at Berkeley(Nogueira & Nascimento, 2017).
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The theory of fuzzy sets has emerged as a tool to
address problems related to information vague, imprecise
or ambiguous, often described in natural language qualitative terms - to be transcribed into numerical
language(Nogueira & Nascimento, 2017).
The use of fuzzy theory allows us to model
mathematically variables vague and imprecise, provided
by knowledgeable people of the study process (BOBILLO
& STRACCIA, 2017).
Are many different applications of the theory of fuzzy
sets, the further fuzzy control, has been applied in the
automation of various areas of production in the industry.
A fuzzy set is a class of objects with a continuum of
association notes. This set is characterized by a
membership function (feature) that assigns each object a
varying degree of association in a numerical range [0,
1](BOBILLO & STRACCIA, 2017).
The
inclusion
notions,
union
intersection,
complement, relation, convexity, etc., are extended to
these and various properties of these notions in the
context of fuzzy sets and are established. In particular, a
separation theorem for convex fuzzy sets is proved
without requiring fuzzy sets are disjoint(ZADEH, 1965)
(Nogueira & Nascimento, 2017).
Inference module: is which defines the logical
connectives used to establish the relationship modeling
fuzzy rules base. It is this module that depends on the
success of the Fuzzy system as it will provide the output
(control) to be adopted by the fuzzy controller from each
fuzzy input(ROBLES, Vazquez, Castro, & Castillo,
2016);
Defuzzification module: which reflects the state of the
fuzzy output variable to a numeric value.
2.5.1
System Mandami
In 1975, Mamdani represented one of the first fuzzy
systems which applied a set of fuzzy rules provided by
experienced human operators to control a combination of
the steam engine and boiler(POURJAVAD &
MAYORGA, 2017).
The main idea of Mamdani method is to describe the
process of states through linguistic variables and use these
variables as inputs to control rules; the rules connect the
input variables to the output variables and are based on
the description of the diffuse state which is obtained by
definition of linguistic variables. It is expected that each
crisp input (real or n-tuple of real numbers) do match a
crisp output and overall system Fuzzy match the each
input an output. In this case, a fuzzy system is a function
Rn R, constructed by a method according to specify
modules 3 (Figure 7)(MUÑOS & MIRANDA, 2016).
Fuzzification module: mathematically modeling the
information of the input variables by means of fuzzy sets.
It is the module that shows the great importance of the
skilled process to be examined, every input variable must
be assigned linguistic terms that represent the states of
this variable and for each linguistic term relevance. The
universe of discourse of each variable was determined by
the linguistic components "Low", "Medium", " High" and
"Low", "Medium", "High" for input and output. It is in
this module that stores the variables and their language
ratings(LEE, 1990);
III.
MATERIALS AND METHODS
3.1 Data
The data used for this study corresponds to
information collected on an industrial hub company
Manaus during production by injection preforms PET
polymer to be used in its entirety for the manufacture of
carbonated beverage containers or not, that process the
preform is stored and then delivered to the beverage
manufacturer, where the final package for the bottling of
the beverage is produced by the blowing process.
All data relating to low linguistic terms, medium and
high, fuzzy set and the universe of discourse, where the
fuzzy rule-based system is generally derived from the
knowledge possessed by an operator or an expert on the
functioning of the system(ARIF, Anoraga, Handoyo, &
Nasir, 2016).
Data were collected in the quality control sector in
packaged preforms in lots of 500 pieces. The Intelligent
System was developed as a solution of the injection
molding process, which is a complex process with a high
number of parameters and variables involved in the
process. The only reference to set the appropriate
parameters based on certain qualitative characteristics of
the produced parts.
The software used to develop this intelligent system
was MATLAB R2013a® by enabling management of
variables and fuzzy operators, and adapt them to any
application without restrictions (CHAVES et al., 2018).
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Fig.7: Structure of the fuzzy logic controller.
Source: Adapted from (Nogueira & Nascimento,
2017).
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The work took place in two phases, the first
characterized by the literature of computational
intelligence applications industries processes, and the
second occurred with the survey and analysis of control
requirements to be used by the proposed fuzzy inference
model.
3.2 Applied Methodology Fuzzy Model
The proposed fuzzy model (Figure 8) shows the
representation scenery inference system Silo temperature
control of the injection molding machine where the expert
daily controls the resin drying process, process done
manually, in accordance with the information and
feedback from inspections of batches produced and
analyzed by the quality control department.
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Low (B)
Ideal (I)
Residence
Time
[12:10]
High (A)
Low (B)
Ideal (I)
[1000:
6000]
Initial
moisture
High (A)
Fig.8: input and output variables of the proposed system.
Source: Authors (2017).
3.2.1 Misty Variables
The input and output data representing the schematic
forms of the fuzzy system, through the amount of data in
kilos PET polymer grains, dew point, air flow, residence
time in the silo, initial moisture content, grain size,
temperature grain and outlet temperature.
Table 1 presents the linguistic variables, as well as
linguistic labels defined for all variables, the universe of
discourse and its description.
Table.1: Description and results of the linguistic
variables.
VARIABLE
language
CLOUD
Y SET
UNIVER
SE OF
SPEECH
DESCRIPTI
ON
[10:50]
The lower the
dew point of
the
higher
speed
air
drying, where
the drying air
Input
Low (B)
Dew point
Medium(M)
High (A)
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Low (B)
Ideal (I)
[12:10]
Grain size
High (A)
is
greater
absorption
capacity.
It is time that
the PET bead
is inside the
dryer. To PET
should be four
to six hours. It
depends
on
the size of the
dryer and the
resin
consumption.
The
absorption of
water by the
PET
resin
occurs until an
equilibrium
concentration
depends
on
various
factors such as
time
and
storage
temperature,
relative
humidity
of
atmosphere,
crystallinity,
grain size and
shape.
The
smaller
the grain size,
the higher the
equilibrium
moisture
of
the resin. This
effect
is
attributed to
the
greater
surface area to
adsorption
(for a same
amount
of
sample,
the
smaller
the
grain,
the
greater
the
total surface
area).
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Low (B)
Ideal (I)
Temperatu
re Grain
High (A)
Low (B)
Medium
(M)
Resin
Quantity
High (A)
Output
Low (B)
Ideal (I)
Temperatu
re
High (A)
All polymers
have
a
suggested
drying
temperature
range. A long
[12:45]
drying
time
and extreme
temperatures
can damage
the material.
PET polymer
in the silo
count should
not exceed the
[450: 550] consumer
PET
which
the machine
produces in 1
hour.
Maintain the
effective
temperature of
grains
[155: 190] between 160 °
C - 180 ° C
(measured at
the
dryer
outlet);
Source: Authors (2017).
[Vol-5, Issue-8, Aug- 2018]
ISSN: 2349-6495(P) | 2456-1908(O)
Fig.10: Variable Dew Point.
Source: Authors (2017).
Residence time of matter- the residence time of the raw
material in the silo is the time that the PET resin is inside
the dryer silo. For PET, must be four to six hours (Figure
11).
Fig.11: Variable Residence Time.
Source: Authors (2017).
The Initial Moisture of the grains- should not exceed
3.000ppm (0.3%) prior to fusion. PET resin by water
absorption occurs until an equilibrium concentration
depends on various factors such as storage temperature
and time, so it is recommended careful storage in cool
environments and covered (Figure 12).
Descriptions of the variables of the proposed system
are: Low, Medium and High.
Variables Inputs:
The Amount of PET Resin - the amount of PET resin in
the dryer silo consumption must not exceed the machine
continuously produces in 1 hour, 500 Kg / h (Figure 9).
Fig.12: Changeable Initial moisture.
Source: Authors (2017).
Figure 9: Changeable Amount of resin.
Source: Authors (2017).
Grain Size- the smaller the grain size, the higher the
equilibrium moisture of the resin. This effect is attributed
to the greater surface area to adsorption (for a same
amount of sample, the smaller the grain, the greater the
total surface area), this hypothesis is supported by the
equilibrium moisture results obtained by PET resin
(Figure 13).
Grain dew point - the lower the dew point of the air, the
greater the rate of drying, where the drying air is greater
absorption capacity (Figure 10).
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International Journal of Advanced Engineering Research and Science (IJAERS)
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[Vol-5, Issue-8, Aug- 2018]
ISSN: 2349-6495(P) | 2456-1908(O)
Fig.13: Variable Size grains.
Source: Authors (2017).
Temperature Grain- water absorption resin, should keep
in storage the resin at 25 ° C ambient temperature, with
temperatures controlled in the manufacturing areas.
(Figure 14).
Fig.16. Inference rules of linguistic variables.
Source: Authors (2017)
Fig.14: Variable Temperature Grain.
Source: Authors (2017).
Output:
Temperature Control in bin - corresponds to the
effective temperature of grains between 160 ° C - 180 ° C
(measured at the dryer outlet), if correct change in
acetaldehyde content (Figure 15).
3.2.3 System Parameters
To perform system controls was used R2013a®
MATLAB tool that used the Fuzzy Logic Toolbox and
Table 2 shows the summary of system parameters on the
use of this tool.
Table.2: Summary of system parameters.
TYPE
METHOD
DEFUZZYM ET
HOD
Fig.15: Variable Temperature out.
Source: Authors (2017).
3.2.2 Rule Base
Through the knowledge of experts were obtained the
information necessary to create the consistency of the rule
base.
To answer the problem posed were created major
Inference Rules Bases of linguistic variables resulting in
729 combinations, applied in this fuzzy solution, where
part of it is shown in Figure 16, the construction of a
fuzzy rule system also should check out no unnecessary
rules and which can be removed from the system.
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"Mamdani
"
'Min'
'Centroid'
INPUT:
[Strut 1x6]
OUTPUT:
[Strut 1x1]
RULE
[Strut 36]
Source: Authors (2017).
The response of the
process is a fuzzy set
for each rule.
Used to be the
connector
system
rules.
Being adherent and
computationally
simple.
6 input variables
One output variable
729 rules in total
In the literature appear several Fuzzy numbers, the
most common are triangular, trapezoidal and bell-shaped.
Among them, the best fit to the proposed model was the
triangular and trapezoidal, since it works the averages
centered on a given range, whose extreme values are
related to the mean and standard deviation functions.
IV.
RESULTS AND DISCUSSIONS
After inspection of a sample of the produced batches are
considered failed lots whose Acetaldehyde indices have
up to 4 ppm values as specified in the standard for the
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International Journal of Advanced Engineering Research and Science (IJAERS)
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[Vol-5, Issue-8, Aug- 2018]
ISSN: 2349-6495(P) | 2456-1908(O)
beverage manufacturer, this information is passed on to
technical production which thereafter alter the adjusting
the polymer drying silo temperature.
A simulation with use of real situations of arguments
where the model can evaluate the linguistic variables of
predefined input generating information to support the
expert decision in controlling the optimum temperature of
the silo during the manufacturing process of the preform
was held. Table 3 shows an example of results of the
proposed fuzzy inference model.
Fig.17: Results shown from inferences.
Source: Authors (2017).
Table.3: Simulation of the proposed fuzzy inference
model.
D.P.
R.T.
I.M.
G.S.
10
3
1000
45
9
4500
50
10
5000
15
4.5 1500
40
8
4000
20
4.0 1700
35
6
2500
25
5.5 2000
30
5
3500
35.5
7
3000
Source: Authors (2017).
1
9.0
10.0
2.5
8.5
3
6
4
5
7.5
Te.Gr. Qt.Rs.
9.5
40
45
10
35
15
25
20
22.5
30
450
545
550
470
540
490
520
510
500
530
Output
161
161
161
162
167
168
172
173
173
173
In Table 3, it is seen that the output values are within
the limits silo temperature tolerance for non-generation of
acetaldehyde in order to evaluate the appropriate values
of the input variables, which result in the drying process
of PET resin. And allowing the specialista on better
regulation of temperature.
By varying the input values is possible to assess the
outputs by the proposed system, obtaining a value that
allows support in decision-making with respect to the silo
temperature control, there is the following situation for
example, if the dew point is -35 ° C, the residence time is
6 hours, initial moisture content is 2500ppm (0.25%),
6mm² the grain size, grain temperature is 25 ° C and the
amount of resin is 520kg / h., then the result will be the
172 ° C temperature, as shown in simulation performed
and observed in Figure 17.
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In the graph of Figure 18 has the development
performance of the outlet temperatures from the values of
the input linguistic variables, where the optimal
temperature for the non-generation of acetaldehyde, and
not affect the degree of crystallization of the packaging,
no loss the intrinsic viscosity of the resin and loss of
physicochemical and mechanical functions, that are on
average 172 ° C
Fig.18: Evolution of the temperature performance.
Source: Authors (2017).
In Figure 19, we note that the residence time of the
resin in the injection molding machine-drying silo must
not exceed 6 hours and the amount of resin should not
exceed 480 kg, approximately.
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International Journal of Advanced Engineering Research and Science (IJAERS)
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[Vol-5, Issue-8, Aug- 2018]
ISSN: 2349-6495(P) | 2456-1908(O)
ACKNOWLEDGEMENTS
The Institute of Technology and Education Galileo of the
Amazon (ITEGAM) PPGBP, UFPA, for supporting this
research.
[1]
Fig.19: Graph of linguistic variable residence time.
Source: Authors (2017).
[2]
Figure 20 shows the optimum temperature of the grain
should be maintained between 20 to 25 ° C for a resin
amount not exceeding 480 kg, approximately.
[3]
[4]
Fig.20: Graph of linguistic variable temperature.
Source: Authors (2017).
V.
CONCLUSION
This study presented a method for application of fuzzy
drying silo temperature control of the injection molding
machine PET polymer. The used model input parameters
preset by the resin manufacturers.
The results showed that, in general, the proposed
inference model enabled, from the input information,
determine ideal temperature of the silo for the production
of preforms is carried out within the quality standards
required by the beverage manufacturer, ie, with
acetaldehyde content below 4ppm. Based on these results,
it can be said that the fuzzy inference model proposed,
can be considered as an important classification tool
temperature control, showing that the Fuzzy method is a
promising tool for this classification, it is suggested
search Fuzzy an interconnection system controls the
injection molding machine so that a synchronized control
is carried out with temperature control sensors, being a
fully automatic system,
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[5]
[6]
[7]
[8]
[9]
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